Category Archives: Scripts

Multi-day calendar events in Google Apps Script

You can create events using the Calendar Class in Google Apps Script. However, only for regular (not all day  events) you can set both the start and the end time. For all day events, you can only set one date, so they will always be one day only. Then how can you create all day events?

There are a few workarounds:

  • Create a regular event and set the start and end time to midnight; remember to specify midnight of the day after the end day. The drawback is the event fills the whole space for a day in your calendar overview, rather then just a line at the top as with all day events.
  • Create a all day event series, so you have a sequence of one-day all day events; this looks already a bit nicer, but in the calendar view, from a single event yio can not see how long it last.
  • Create an event from a description, this creates real multi-day all day events.

So creating an event from a description seems the best way to go. This is worked out in a new function, createMultiDayEvent( calendar, title, startDate, endDate ). Continue reading

Stylesheets in Google Apps Script UiApp

Despite the documentation, it is quite well possible to use style sheets in a Google Apps Script UiApp.

The documentation of Google Apps Script is quite clear: “… there is no way to use custom style sheets in UiApp.”. This is mentioned in relation to the stylename methods, such as setStyleName(). However, most elements in the UiApp have the  setStyleAttributes() method. This accepts an object with style attributes, e.g.

label.setStyleAttributes({background: "black", color: "green"});

This is how you can assign style information to an element.

The essence of a style sheet is to separate the formatting from the content and the program logic. Separate style sheets make the script more readable and enable you to change the appearance and layout of all pages in a UiApp, just by editing one single file.

In Google Apps Script, you can realize this by setting the style attributes using named objects, and define these objects in a separate file. The following example shows how this works.

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ObjDB: the easy way to store data with Google Apps Script

There are various ways in Google Apps Script to store data, a common way is to store data in a spreadsheet. Spreadsheet data is relatively easy to access, and sample code is provided to read data from a spreadsheet into an array of JavaScript objects, and to write from objects to the spreadsheet. For more advanced database functions (update, select, delete), you have to do some more programming.

For larger applications, you may want to use MySQL or other databases via JDBC, Again, some sample code is provided, but this time not to read/write to and from JavaScript objects. A lot more coding is required, especially to link the fields in each record to the field name, instead of just the offset in the results rows.

To make it easier to work with data in Google Apps Script, both from spreadsheets and from JDBC databases, I have developed the ObjDB library. This is a set of functions, with which you can open a spreadsheet or database, and do all the basic operations: select, update, insert, delete. Functions are the same for spreadsheets and for JDBC databases, except the different parameters for the open() function, so if you start with data in a spreadsheet, and later move the data to a database, there is hardly any code to change.

To show how the library works, I prepared a demo spreadsheet with script. Open the link, it should create a new copy of the spreadsheet, if not, copy it yourself. Then go to ToolsScript editor…, and run any of the functions to see it in action.

Note that the script in this spreadsheet includes the objDB library, see under ResourcesManage Libraries….

For more documentation, reference and source code, go to http://googlescripts.harryonline.net/home/objdb.

How to index Project Gutenberg files

project_gutenberg_logoProject Gutenberg offers over 40,000 free ebooks: choose among free EPUB books, free kindle books, download them or read them online. Recently, they have added support for Dropbox, so you can download ebooks directly to your Dropbox account. It will create a folder ‘Apps/gutenberg’, and will store all ebooks in that folder.

After a while, this Dropbox folder will have a long list of files, all with names like pg1234.epub and pg5678-images.epub. They have some meaning, but which file contains which title? Of course, you can rename each ebook  after downloading, but this is extra work, and I want a smart solution.

pg_filelist

So I created a script to create an index for all ebooks–at least, for those in EPUB format. Now there is simply an index.html file, which will open in any browser. It shows the file name, together with the creator, title and language. Depending on how you view the index.html file, the links may be clickable, In any case, you can quickly see which file is which book.

pg-index

The script works on any set of EPUB file, but usually, they will have a more meaningful name and there will be less need for a script like this.

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Sprintf: merge text and variables in Javascript

The function sprintf is common in many programming languages, as a way to merge programme variables in a text string. It has good options for formatting, such as outlining text string, or setting the precision of numbers. In many cases, you don’t need those, and a simple function that just inserts the variables at the right place is fine, and a better option in order to keep your JavaScript code short. See the example below:

// Simple string concatenation
var html1 = '<a href="' + url + '">' + link + '</a>';

// Using sprintf
var html2 = sprintf( '<a href="%s">%s</a>', url, link );

In this article, I share a simple function doing string replacements. For sprintf alternatives with the full functionality, just Google on ‘javascript sprintf’, and you will find some good versions. If you don’t need all that, read on.

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